This is the EMS Linear Servo Conversion Kit for the Futaba S3003 Servo.

FEATURES

Converts the rotational output of the S3003 servo to linear output
Ideal for throttle control in airplanes and gas cars to animatronics
and actuating remote control submarine surfaces
Uses a drum to coil and uncoil the output arm at a fixed radius to
ensure linearity
Control horn is confined in 5 degrees of motion to maximize precision
Two year limited warranty through EMS beginning at date of purchase